Twelve lifestyle choices and conditions that fuel dementia have been identified by the World Health Organisation (WHO) in the most definitive list ever of how to avoid mental decline in later life.

New guidelines based on analysis of decades of research found that physical inactivity, smoking, eating an unhealthy diet and drinking excessive alcohol significantly increased the threat of diseases such as Alzheimer’s.

Medical conditions including diabetes, high blood pressure, high cholesterol and obesity also played a role in the development of cognitive decline and full-blown dementia. It also warned of a link between hearing loss and depression.

Dr Tedros Adhanom Ghebreyesus, the WHO director general, said: “The scientific evidence gathered for these guidelines confirm what we have suspected, that what is good for our heart is also good for our brain.”

Tens of thousands of people in Ireland are currently living with dementia.

Under the new guidance, over-65s are advised to do at least 150 minutes of moderate exercise a week.